added Konsole-like 24-bit color control sequences
use foogroundColor to store fooRed in 24-bit mode
reordered ScreenChar elements for byte alignment
style fixes
added - (NSColor*)foogroundColorForChar:(screen_char_t)
further style fixes
corrected a few typos
logic and style fixes
combined {fg,bg}Is24bit and alternate{Fore,Back}groundSemantics into {fore,back}groundColorMode
did some math, got 16-bit color for free
fix some logic, and cleanup
removed 24-bit color from CURSOR_BOX
Revert "removed 24-bit color from CURSOR_BOX"

This reverts commit ba228e607aa10713378afb2c115c28e3516eb3d9.
removed 24-bit color from CURSOR_BOX
logic fix
added 24-bit color to underline
style fixes
type changes
_drawCharacter:alternateSemantics -> _drawCharacter:fgColorMode
readded attribute tests to ForegroundColorsEqual